While their peers sweat out their next geometry quiz, high school students Courtney Dressing and Rafael Morozowski are sweating out the commencement of surface activities with the rest of the Mars Exploration Rover team.

Dressing, a sophomore from Virginia, and Morozowski, a senior from Brazil, are members of an international team of students working directly with scientists and engineers overseeing the science payload on the Mars Exploration Rovers. The two 16-year-olds are the first of 16 "Student Astronauts" aged 13 to 17 who, all told, call twelve different nations home. They won their places aboard the Mars Exploration Rover team through an essay contest run by the Planetary Society followed by oral interviews. This is the first time that an international group of young people has been selected through open competition to participate in an active planetary spacecraft mission.

"We were there in the control room when Spirit landed," said Morozowski. "I was totally speechless. Then, we were there when the first pictures from Mars came back. We were seeing great things that were over 170 million kilometers (about 100 million miles) away. It was fascinating."

But Dressing and Morozowski, and the 14 Student Astronauts to follow, are there to do more than observe. They are involved in one of three programs where high school students become official Mars Rover participants. As Student Astronauts, Dressing and Morozowski have their own offices, attend team meetings, serve as ambassadors communicating to the world about life inside a Mars mission team, and are tasked to process images taken of the rover's "MarsDial".

"The MarsDial is a sundial but this one is different and cooler because it is on Mars," said Dressing. "It is used by the rover's cameras for calibration purposes. We are going to process these calibration images, add hour marks electronically and provide them online. This should gets kids excited about space exploration and help them and their teachers learn about time and celestial motion."

Also receiving an education from the Mars imagery on a daily - if not hourly - basis, are the full-time scientists and engineers working on Spirit. During this morning's briefing, Cornell University's Dr. Jim Bell, the mission's payload element lead for the Panoramic Camera, revealed some more remarkable imagery of Columbia Memorial Station. This latest "Postcard From Mars," downloaded using the rover's high-speed, high gain antenna, depicts the view north -- behind the rover. The image has an apparent slope with relation to the horizon due to a tilt of the lander deck. There is a dune-like object to the right side of the image that has piqued the interest of the science team and may become a future target of the rover's onboard instruments. On the left of the image, the circular topographic feature dubbed Sleepy Hollow can be seen along with dark markings that scientists think may very well be surface disturbances caused by the airbag-encased lander as it bounced and rolled to rest.

"Originally, we thought that prominence right in front of the rover was a big rock," said Matt Wallace, a mission manager at the Jet Propulsion Laboratory in Pasadena, Calif. "But after we downloaded the more high-resolution images, we realized it is actually just a very, very dirty, dust-coated airbag."

The airbags themselves have become a topic of conversation among the team. An attempt during Sol 5 to fully deflate and retract an airbag at the front-left side of the rover was not as successful as the team had hoped. Commands will soon be beamed up to Spirit to again retract the uncooperative airbag and then lower the lander's pedestal.

"This rover is a thoroughbred, and I have a great deal of confidence we could drive right over that airbag," added Wallace. "But we are 100 million miles away and have several other options for egress, so we will take our time and get it right. We are going to be brave but we're not going to be stupid."

While Spirit's exploration is just getting warmed and Opportunity is waiting for its moment in the martian sun, JPL's first duo of Student Astronauts is wrapping up a one-week stint living and breathing the red planet. But while their tour of duty ends Saturday, their interest in the mission will continue, apparently far beyond the rover's lifespan.

"After I finish my education I think I want to work right here at JPL," added Dressing. "I love space and I think this is a great place for that. After all, where else can you go to Mars?"

For more information about the Student Astronauts, the MarsDial, and a coded message on the cover of a digital video disk that carried more than three million names to Mars, see http://www.redrovergoestomars.org/index.html .

Spirit's twin Mars Exploration Rover, Opportunity, will reach its landing site on the opposite side of Mars on Jan. 25 (EST and Universal Time; Jan. 24 PST). The rovers' task is to explore for clues in rocks and soil about whether the past environments in their landing areas were ever watery and suitable to sustain life.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington. Images from Spirit and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu .